1. Field of the Invention
This invention relates to well equipment that may be located anywhere in a well and is particularly concerned with a method for preventing particles of debris from accumulating around or in the working mechanisms of such equipment.
2. Description of the Prior Art
Well equipment such as packers, check valves, gas lift valves, sliding sleeves, side pocket mandrels, retrievable plugs and the like are frequently used in a variety of different types of wells including producing wells, injection wells, observation wells and service wells. Packers are normally used to seal off the annular space between the tubing string and the casing in a producing well, thereby forcing production fluids upward through the tubing string to the wellhead. Retrievable plugs are normally located in either the casing or the tubing string of a well where they serve to prevent the flow of fluids. Gas lift valves and side pocket mandrels may be used in the tubing string or in the annular space between the tubing string and the casing. No matter where equipment is located in a well, it will normally be covered with some type of fluid. For example, a packer located in the annular space between the tubing string and the casing will normally be surrounded with packer fluid that extends from the top of the packer to the top of the well. This fluid prevents the casing from collapsing inward under the force exerted by pressures in the rock formations surrounding the casing. Similarly, tubing plugs set in the tubing string will normally be covered with production fluids present in the tubing string or with drilling mud that is pumped into the tubing string to kill the well before the plug is inserted and set in place.
Small particles of solid debris in the form of slag, sand, mill scale, corrosion products, metal cuttings, rock cuttings and the like will normally be present in the fluids that cover well equipment whether they be packer fluids, production fluids, drilling muds, brine or similar liquids. Any of these particles that have a density greater than the density of the fluid they reside in may settle downward through the fluid and collect on top of the equipment which the fluid covers. From here they may work their way into small clearances between the equipment and the walls of the tubing string or casing, depending on where the equipment is located, and can cause sticking problems or otherwise interfere with the operation of the equipment. Also, the collection of debris around the top of certain types of equipment may make it difficult to grasp hold of the equipment when it is desired to retrieve it from the well.